1. Field of the Invention
The present invention relates to a method of determining a quality of a cladding layer and a laser build-up apparatus, and relates to, for example, a method of determining a quality of a cladding layer for a valve seat and a laser build-up apparatus for the valve seat.
2. Description of Related Art
A laser cladding process (so-called a laser cladding method) that irradiates a laser beam while a metallic powder is being supplied to form a cladding layer is used, for example, to form a valve seat of a cylinder head.
Japanese Unexamined Patent Application Publication No. 09-192861 discloses an apparatus in which the intensity of light emitted from a melt pool in the laser cladding process is observed by a plurality of optical sensors and the presence or the absence of an abnormality in the cladding layer is determined.
The present inventors have found that holes (blow holes) are generated when excess metallic powder (excess powder) deposited at the front of the direction in which a melt pool moves aggregates, the state of the excess metallic powder becomes a semi-molten one since a laser beam comes close to it, the excess metallic powder becomes balls (ball-shaped metal aggregates) having a relatively large size, and then the balls are absorbed in the melt pool. In the apparatus disclosed in Japanese Unexamined Patent Application Publication No. 09-192861, only the intensity of the light emitted from the melt pool is observed and a function of detecting the above ball-shaped metal aggregates, which generates such holes, is not included. Therefore, it is impossible to accurately determine the quality of the cladding layer.
The present invention has been made in order to solve the above problem and aims to provide a method of determining a quality of a cladding layer and a laser build-up apparatus capable of accurately determining the quality of the cladding layer.